Supabase does the auth emails. If you make a post and have the service email it for you, it uses Sendgrid which seems to make it past the spam folder most of the time.
make sure you got the right dns records in place as well. I haven't looked at your mail headers yet[0] but you probably want to send from a separate subdomain than the one you use for everyday use (like for team@slowsocial.us).
[0] This may be seen as a back-handed way of saying I have no intention of signing up, but I didn't intend for it to be.
